Numerical simulation of tube profile growth during spray forming process Numerical simulation of tube profile growth during spray forming process

Numerical simulation of tube profile growth during spray forming process

  • 期刊名字:宝钢技术研究(英文版)
  • 文件大小:132kb
  • 论文作者:REN Sanbing,FAN Junfei,LE Hair
  • 作者单位:Advanced Technology Division
  • 更新时间:2020-11-11
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论文简介

Baosteel Techrical ResearchVolume 5 ,Number 3,September 2011 ,Page 15Numerical simulation of tube profile growth during spray forming processREN Sanbing, FAN Junfei and LE HairongAdvanced Technology Division, Research Institute ,Baoshan Iron & Steel Co., Ltd., Shanghai 201900, ChinaAbstract: Spray forming is a new type of metal material forming process , which can produce metal blanks such as billet,tube .plate etc. A mathematical model has been developed to forecast the shape evolution of tube billets during the sprayforming process. The atomizer mass flux a, ,radial distribution coefficient b. , draw velocity and diameter of mandrel wereconsidered in this model and the influence of different parameters such as metal flowrate , draw velocity of mandrel,diameter of mandrel on the tube' s shape change were simulated and analyzed in this paper. The simulation results obtainedfrom this model can be provided to engincers as reference.Key words: spray forming; mandrel; tube billet; simulationdoi: 10. 3969/j. issn. 1674 - 3458.2011.03.003the mathematical modeling and established quantitativeguidelines for optimizing the evolution of microstructures1 Introductionin the droplets consolidation. The work of Cai and hisSpray forming has been identified as a process capablecolleagues should also be mentioned. They carried ouof manufacturing near-net- shapecomponents foshape modeling in a manner similar to that of the presentadvanced technologies of the aerospace , defense, ancstudy ;however , they did not include the scanning motionchemical industries. It is achieved by atomizing a liquidof the gas atomizermetal sheet with an inert gas to form molten dropletsIn the present study, a different tube billet formingwhich are subsequently deposited onto a rotatingmodel was set up to investigate the tube profile evolutionsubstrate. A coherent , fully-dense preform is produced asmechanism. The effects of the various parameters for thethe continuous movement of the substrate and thespray forming process such as metal flowrate , mandrelatomizer , along with careful control of the gas-to-metaldiameter and mandrel withdrawal velocity wereflow ratio. The preform has a fine equiaxed grainanalyzed. The calculations can provide initial guidance tostructure sized 10 - 100 μm with esenially no engineers in operating the spray forming process.macroscopic segregation, and therefore, it allows alloyhomogenizing heat treatments to be avoided or reduced.2 Mathematical model for simulation the tubeChemical homogeneity and fine uniform microstructuresbillet profileof the deposit are unique features of spray formedmaterials. Comparing with the conventional casting anThe spray forming tube billet process is shown inpowder metallurgy ( PM) processes, the spray formingFig.1. The molten metal was atomized into differentprocess shows the advantage that different depositsized droplets by inert gas and these small droplets thengeometries can be produced by varying the substratefly into the mandrel deposition at high velocity. At theconfiguration and motion.same time, the mandrel movement in the verticalHowever,the spray forming process is very complex,direction rotated around its axis. With the atomizedand the final shape of a cylindrical bllet is determinedmolten metal deposition on the mandrel continuously , theby geometrical factors such as rotation, scanningdeposition layer finally formed into the tube profile.frequency ,angle of incident and withdrawal speed of theMolten metal一billet. Extensive studies on the rod preform shape model, Cruciblewhich is considered to be the most complex and criticalAtomizer。step have been carried out to gain an understanding of=的=仁Inertgasthe spray forming process. Once the preform shape iscalculated, the deposition and thermal history of theMotorSpray coneatomization cone can be analyzed. Frigaard conducted an. Mandrelanalysis of the steady-state and transient-state rodgrowth. Mathur et al. calculated the rod shape bynumerically integrating the change in the height of the中国煤化工rod-surface grid points during spray forming with ascanning atomizer. They demonstrated the importance of.THCNMHGbllet processCorresponding author: REN Sanbing; E-mail: rensb@ basteel. comBaosteel Techrical Research, VoL.5, No. 3, Sep. 20112. 1 Spatial mass flux distributiondeduced from Eq. (7) that the real distance in sprayThe atomizer is the key equipment for the spraylocation away from axis r and distance away fromforming process and has a Laval tunnel in it. Atatomizer h should be calculated before solving thepresent,there are two types of atomizer:one is the freemass flux. A point Q in any location of the mandrelfall type and the other is the closed couple type. Inwhoes intersection angle at the horizontal level equals θspray forming, a stream of liquid metal or alloy iss labeled and its distance away from the pointatomized by high-velocity inert gas and the resultantperpendicular to the atomizer isdroplets are sprayed onto a substrate , forming a bulkr= (1/2dcos 的+下(8)deposit. The droplets spatial distribution need to bewhere l is distance away from the spray axis. In sprayobtained in order to develop an accurate shape modelforming, the mandrel is moving along axis withof the spray-formed bllet. In spray forming , the massvelocity and the l can be devised by followingux M is assumed to be independent from time in theequation:steady spray phase. The dependence of M on thel =l -vt(9)distance r from the spray axis is ofien described asGaussian-like distribution for a special set of atomizerWhereas the spray distance,and delivery tube.h =h, - 1/2dsin θ(10)M =anexp(-b。r2)(1)where h, is perpendicular distance away from thewhere M is the mass fux in the spray center,r is themandrel axis. Then the accumulated thickness T ( mm)radial distance of any point, an and b, are maximumcan be obtained from the following equation:mass flux ( mm/s) and radial distribution ceoffcientT= [\SD(r,h)in (0 +w)dr(11)Because the spray of droplets always expandswhere λ is adhesion factor, s is shading cefficienttowards the substrate , the mass flux distribution in the(Fig. 2(b)) ,can be calculated asspray cone varies with the spray distance. But the masse,ej≥0,S =1(12)spray velocity satisfies the following relation:e.Cy <0,S =0(13)aoπ(dr)2 = am(dr)2(2)If the coordinate of Q in time1 is (x,y,z) ,then thedro/dr = h,/h(3)coordinate of Q in time1+8(xI** ,y",z**) is:By solving Eq. (3) and Eq. (2) ,one can devise thex2*W =x +δte"e*(14)mass flux equation:ylW =y+δte"e'(15)a = ao(h/h)"(4)zimew =z +δte"e'(16)If the distribution of the mass flux at one referencedwheree' ,e ,e' are unit vectors of the x axis,y axis andspray distance is known, the distribution at any otherZ axis respectively.distance can be deduced according to the conservationof mass:Atomizera广aep(bor)rdrd.o =aexp( - brF)rdrd8.,Top viewBy solving Eq. (4) and Eq. (5) ,one can devise theequation of the radial distribution cofficient:b。/b = (h0/h)2(6)亚Then the mass flux at any distance h is given asD(r,h) =ao的)》(0简门 (7)(细) Side view and top view(b) Shading vector indication中国煤化工' caculatio2.2 Shape model of the spray-formed tubeIn spray forming,as shown in Fig. 2, the mandrel isMHCNMHGmoving along the axis with velocity v and rotating2.3 Parameters used in simulationaround the axis with angle velocity w. It can beThe parameter and constant used in spray formingREN Sanbing, et al. Numerical simulation of tube profile growth during spray forming process1tube bllt were listed in Table 1.rotation velocity was 30 rad/ min , and the simulationtime cycle was 30 s,60 s,120 s,180 s,240 s andTable 1 Parameters and constants used in simulation300 s respec-tively. It can be seen from Fig. 3(a) thatthe deposition layer on the left side of the tube isItemDatathicker than the right side because the atomizer isSpray distance/ mm500perpendicular on the left side of mandrel and there isMandrel rolation velocity/(r ●min“10- 80no spray cone covering the right side in the beginning.Mandrel moving velocit/(mm.s" ")1-5The deposition layer constantly grows on the left sideMetal flowrate/(kg . min ')5-20ind moves rightward at the same time, since theMandrel diameter/ mm40 -200mandrel moves leftward of the middle part under theatomizer,as seen in Fig. 3(b) and Fig.3(c). Whenthe mandrel moves leftward continuously, the spraycone covers the whole area of the substrate and the3 Results and discussiondeposition layer increases obviously in the middle andThe shape profile of the spray-formed tube billeton the right part. While the depositon layer decreasesduring different process parameters . such as spray time,on the left side of the mandrel,as seen in Fig. 3(d).metal flowrate , mandrel diameter and mandrel movingFrom Fig. 3(e),it can be found that the depositionvelocity were simulated.layer does not change on the left side and thdeposition velocity increases on the right side bu3.1 Shape evolution with different time stepsdecreases in the middle. Finally ,when the right side ofThe shape profile of the tube billet during spraythe mandrel moves under the atomizer , the depositionforming with time forward is shown in Fig. 3. In thelayer on the right side grows fast and almost remainspresent study, the mandrel moving velocity wasthe same in the middle. Thus , the deposition layerI mm/s,the spray distance was 500 mm , the mandrelgrows well- distributed and forms the shape of the ube.昌s(量-500200400600Length 1 mmLength/ mm(a) 30s(b)60s唇soF昌5量-500Lengh/ mm() 120s(d) 180s昌soF(e)240s(0 300sFig.3 Tube profile in dfferent times3.2 Influence of metal flowrate on the tube shape diame中国煤化工。elivery tubes wasThe inner diameter of delivery tube affects the metalsimula:MHCNMHG300sandotherflowrate in the spray forming process. In the presentparameters were kept same as above condition. It canstudy,the tube shape evolution under different innerbe seen from Fig. 4 that the metal flowrate is low8Baosteel Technical Research, Vol.5, No.3, Sep. 2011(10.6 kg/min); while using the 5 mm diameterthickness becomes thinner with an increasing mandreldelivery tube ,the final deposition thickness is 6.5 mm.diameter. This can be explained that the mandrel areaWhen using 6 mm diameter delivery tube, the metalincreases with the diameter becoming larger. While theflowrate increases to 12. 6 kg/ min and the depositionwhole metal quantity does not change , the depositionlayer reaches 10. 8 mm. Finally, the shape profile islayer on the small mandrel is thick and thin in the large21 mm over the mandrel as the metal flowratediameter mandrel. However the diameter of the mandrelincreases to 15. 8 kg/min when applying the 7 mmdoes not afct the time forming stable deposition layerdiameter delivery tube.since the moving velocity is kept the same in the3.3 Influence of mandrel moving velocity on thepresent simulation.tube shape昌sThe efect of mandrel moving velocity on the shapeprofile is shown in Fig. 5. When the mandrel velocity isI mm/s,2 mm/s and 4 mm/s , the deposition thicknessreaches 5. 4 mm,12.3 mm,and 22. 5 mm respectively.200400600Length 1 mmIt can be concluded that the deposition layer becomes(a) 1 mm/sthinner with an increasing mandrel moving velocity.This can be explained that when the mandrel moving昌50velocity changes, the area of the spray cone extendedarea changes too. Since the total metal quantity is至-50fixed, therefore, the deposition thickness varies in00different deposition areas at the same time. If the1.ength / mmmandrel moves fast, the spray cone covered area is(b)2 mm/slarge and the deposition layer is thin and vice versa.昌sofe -500(C)4 mm/sLength/ mmig.5 Tube profile under dfferenet mandrel moving velocity(a) 5 mm diameter50室-5060Length 1 mm :(a) 80 mm(b) 6 mm diameterL.ength 1 mm(C) 7 mm diameter(b) 120 mmFig.4 Tube profle sprayed with dflent flowrate昌s03.4 Influence of mandrel diameter on the tubeshapeThe effect of mandrel diameter on the tube shape is中国煤化工00shown in Fig. 6. When the diameter of the mandrel isMHCNMHG80 mm, 120 mm, and 160 mm, the thickness of thedeposition layer reaches 15.2 mm, 9.5 mm and6.4 mm respectively. It can be seen that the depositionFig.6 Tube profile under diferent mandrel diametersREN Sanbing, et al. Numerical simulation of tube profile growth during spray forming process194 Conclusionsprinciples and applications [ J ]. Intermational Journal ofPowder Metallurgy, 1993 ,29(4) :321-329.(1) The deposition layer formed gradually on the[3] Lawley A. Melt atomization and spray deposition - qucmandrel surface with the mandrel moving and thevadis [ C ]//Spray Deposition and Melt AtomizationSDMA 2000. German:University o Bremen ,2000:3- 16deposition layer growing from forward to backward.(2) Given the same mandrel moving velocity, a[4] Lavemnia EJ,Rai G and Grant N J. Rapid solificationprocessing of 7XXX aluminum aloys:a review[J].large inner diameter delivery leads to a higher metalMaterials Science and Engineering A.1986,79:211 - 221.flowrate and the formation of a thicker deposition layer[5] GrantPS, Cantor B and Katgerman L. Moelling ofand vice versa.droplet dynamice and thermal histories during spray(3) Given the same metal flowrate and mandrelforming. 1. Individual droplet behaviour [ J ]. Actadiameter ,if the mandrel moves fast , the deposition layerMetallurgica et Materialia, 1993 ,41(11) :3097 - 3108.is thin and if the mandrel moves slow, the depositionlayer is thick. Given the same mandrel moving velocity,the deposition layer in the mandrel is thin, when themandrel diameter is large and thick ; the deposition layeris thick , when the mandrel diameter is small.References[1] Singer ARE. The challenge of spray forming [ J ].Powder Metallurgy ,1982 ;25(4):195.REN SanbingFAN JunfeiLE Hairong2] LeathamAG and Lawley A. The Osprey process:中国煤化工MYHCNMHG

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